class Redis::Cluster::Slot

def assign_node_key(mappings, slot, node_key)
  mappings[slot] ||= { master: nil, slaves: Set.new }
  if master?(node_key)
    mappings[slot][:master] = node_key
  else
    mappings[slot][:slaves].add(node_key)
  end
end

def build_slot_node_key_map(available_slots)
  available_slots.each_with_object({}) do |(node_key, slots), acc|
    slots.each { |slot| assign_node_key(acc, slot, node_key) }
  end
end

def exists?(slot)
  @map.key?(slot)
end

def find_node_key_of_master(slot)
  return nil unless exists?(slot)
  @map[slot][:master]
end

def find_node_key_of_slave(slot)
  return nil unless exists?(slot)
  return find_node_key_of_master(slot) if replica_disabled?
  @map[slot][:slaves].to_a.sample
end

def initialize(available_slots, node_flags = {}, with_replica = false)
  @with_replica = with_replica
  @node_flags = node_flags
  @map = build_slot_node_key_map(available_slots)
end

def master?(node_key)
  !slave?(node_key)
end

def put(slot, node_key)
  assign_node_key(@map, slot, node_key)
  nil
end

def replica_disabled?
  !@with_replica
end

def slave?(node_key)
  @node_flags[node_key] == ROLE_SLAVE
end